Objective To investigate the changes of serum levels of high-sensitivity C-reactive protein to distinguish community-acquired pneumonia caused by bacteria or mycoplasma pneumoniae in children.Methods To examine the serum levels of hs-CRP of patients with bacteria ( n =50),mycoplasma pneumoniae ( n =50),Virus ( n =50) by the Immunofluorescence method.and The levels of white blood cell(WBC),count of polymorphonuclear neutrophils(PMN) and neutrophil percentage(N) were analyzed.Results The levels of hs-CRP increased to different degrees in patients with bacterial pneumonia or mycoplasma pneumoniae pneumonia.the level of WBC,PMN and N have significant difference btween two groups also( all P ＜0.01 ).The area under the ROC curve(AUC) of hs-CRP was bigger than that of WBC,PMN and N(0.935 vs 0.783,0.807,0.747) and it was Significant difference(all P＜0.05).Conclusion Serum bs-CRP was a better biomarker in the early diagnosis of bacteria and it could effectively dstinguish community-acquired pneumonia caused by bacteria or mycoplasma pneumoniae in Children.